Internal combustion engine



Sept 29, 1942- A c. l.. WALKER 2,297,376

INTERNAL COMBUSTION ENGINE T NEYS.

Sept. 29, 1942. c. l.. WALKER 25292376' INTERNAL coMBUsTioN ENGINE Filed May 1, 1939 2 sheets-sheet 2 l INVENToR.

Patentecl Sept. 29, 1942 UNETED STATESPATENT FFICE INTERNAL COMBUSTION -ENGINE Clinton L. Walker, Piedmont, Calif.

Application May 1, 1939, Serial No. 271,092

15 Claims. t r`(Cl. 123-97) My invention pertains to internal combustion engines, and particularly to a method and means for changing the characteristics of the engine to produce a braking operation.

In my co-pending applications, Serial No.-

Patent No. 2,178,152, I illustrate means disposedbetween the cam shaft and associated valves for raising and shifting the tappets from one set of cams to another. The engine is thereby changed from a four-cycle internal combustion engine to a two-cycle compressor. tion the timing mechanism is also changed So that the firing of the fuel continues. This provides additional resistance by explosive power as the engine operates as a two-cycle engine in the reverse direction. In either instance, a brake load is provided which resists the forward movement of the vehicle.

Similarly, my present invention embodies the concept of producing a brake load by converting the engine from a four-cycle internal combustion.,`

engine to a two-cycle compressor. I have illustrated a rocker arm connected to each tappet, and rocking the arms with an eccentric which is rotated through a train of gears by a hand wheel. An arm extends from the shaft carrying the eccentric, through a connecting link, rotating a shaft which operates an arm to shift the cam shaft axially. A loose connection is provided be- In the latter applica-r tween the arm and the eccentric on the shaft so that the eccentric operates rst to raise the valve after which the arm is operated to shift the cam shaft. A loose connection is also provided between the eccentric shaft and the arm for' shifting the cam shaft to produce a predetermined desired sequence in reverse operation. The arrangement is such that the tappets are first raised before the cam shaft is shifted in either direction. The shifting of the cam shaft connects one of two sets of driving gears to rotate the cam shaft to produce a four-cycle internal combustion engine operation in one position and, in the other extreme position to operate the engine as a twocycle compressor.

It is within the purview of my invention to provide a movable piston in the cylinder head, above the engine piston, to increase the pressure, and therefore the braking power when operating as a two-cycle compressor. Means are provided for adjusting the position of the piston for the purpose of increasing the compression pressure,

when the engine is operating as a two-cycle compressor. Naturally, the braking resistance is limited to the compression of a full charge of air in the cylinder. When a higher rate of compression is desired, the movement of the auxiliary head or piston decreases the clearance space at the pistons top center, to thereby increase the compression pressure and the brake load developed thereby.

Accordingly, the main objects of my invention are to change the operating characteristics of a four-cycle internal combustion engine to a twocycle compressor by shifting the cam shaft axially; to provide a combination mechanism for raising the tappet and shifting the cam shaft for changing the operating characteristics of an engine; to provide a movable head or piston which is adjustable to regulate the clearance when the piston is at top center to vary the compression pressures, and therefore, the brake load of an engine when operating as a two-cycle compressor; to provide a flexible arm between the tappet raising mechanism and the cam shaft shifting d'evice to permit relative movement therebetween when interference occurs; and in general, to pro- `vide a mechanism for changing from a four-cycle internal combustion engine to a two-cycle compressor which is simple in construction, positive v in operation, and economical of manufacture. 30

Other objects and features of novelty of my invention will be specifically pointed out or will become apparent when referring, for a better u nderstanding of my invention, to the following description taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a broken view, partly in section and partly in elevation, of a combination engine and compressor and the mechanism for changing from one to the other, embodying features of my invention;

Fig. 2 is a broken view of structure, similar to that illustrated in Fig. 1, with the cam shaft shifted axially to the right, as viewed in the gure;

Fig. 3 is a sectional view of the structure illustrated in Fig. 1, taken on the line 3 3 thereof;

Fig. 4 is a sectional view of the structure illustrated in Fig. 1, taken on the line 4 4 thereof;

and,

Fig. 5 is an enlarged view of a cylinder and an adjustable head for varying the clearance above the engine piston when at top center.

The internal combustion engine herein illustrated, is provided with a crank shaft I of conventional form, which drives a cam shaft 2 either through the pair of gears 3 and 4 or through the pair of gears 5 and 6. The gears 3 and 4 are the timing gears which operate the valves and, therefore, the engine as a four-stroke cycle internal combustion engine. When the cam shaft is driven through the gears 5 and 6, the engine is then operating as a two-stroke cycle compressor, providing a brake load on the fly wheel and the parts producing the continued driving thereof. A plate 'I is recessed in the side of the gear 3 and is provide-d with a hub which extends through the gear forming a bearing to permit the independent operation of the gear and the cam shaft. The cam shaft is provided with a hub having a ange 8 thereon through which a plurality of pins 9 project from either side. The portions of the pins projecting toward the plate "I are engageable with a plurality of apertures therein aligned with said projections. A similar plate, having a plurality of apertures Il! therein, is recessed in the face of the gear 5 with the apertures I8 aligned with the pins 9 projecting from the right hand side of the flange as viewed in the figure. This provides a driving connection between the flange 8 and the plate having the apertures I8 when the cam shaft is shifted to the right which disconnects the pins 9 from the plate I and changes the operating characteristics of the engine to a two-cycle compressor.

A retainer I I is bolted to the inner face of the gear box, having a flange which projects over the flange on the gear 5 to thereby retain the gear against movement axially of the cam shaft. The gear 5 is provided with a hub I2 from which the flange projects and which forms a bearing to permit the relative movement between the cam shaft and the gear. A plate I4 is mounted on the left hand face of the gear 3, engageable by the flanges on a retainer I3 which is secured to the Wall of the engine block. In this manner, the gears 3 and 5 are mounted for rotation on the cam shaft 2 while being retained against movement normal to the plane of rotation. Either gear 3 or 5 may be connected in driving relation with the cam shaft 2 through the pins 9 which project into the apertures in the faces of the gears, respectively. This is effected through the axial shifting of the cam shaft when the tappets areI raised, as will now be described."

In Fig. 3, I have illustrated Valve tappets I5, resting on cams of the cam shaft 2 and the push rods for operating the engine valves resting on the tappets. Each of the tappets is provided with a slot I6 in which the ends of arms I'I project.'y

The plurality of arms II extend from a shaft I8 which is supported in brackets on the side of the engine block. An arm I9 projects from the shaft I8 on the end of which a roller 28 is pivoted. The roller is aligned with a cam 2l-y which is rotatable on a shaft 22 supported in brackets on the side of the engine block. The shaft 22 has a gear 23 keyed thereto and disposed in mesh with a pinion 24 on a shaft carrying a gear 25 which is in mesh with a pinion' 25 supported on a shaft 21 which is driven through a hand crank 28.

The cam 2I above referred to, is provided with an extending hub 29 having a slot 38 therein in which a pin 3| projects to be relatively moveable to engage one or the other end of the slot. An arm 32 which is preferably flexible, and which is herein illustratedk as comprising a plurality of leaf springs, is mounted in a collar which is also movable relative to the shaft 22 on which it is mounted. A link 33 projects downwardly from the end of the arm 32, engageable with the end of an arm 34, pivoted on a shaft 35, which is journalled in the Wall of the engine block. The ends of shaft 35 carry an arm 35 in which a pin 3l, extending from an operating block 38, is loosely secured. The block 33 projects within an annular recess or groove in the cam shaft 2. Through the rotation of the shaft 35, the arm 3G revolves to shift the block 38, and, therefore, the came shaft axially.

A collar 43 on the end of the arm 32 is disposed about the shaft 22 and is provided with a slot 4I in which a pin 42, secured to the shaft 22 projects. This loose connection between the shaft 22 and the arm 32 permits the actuation of the valve tappets I5 to have them raised before the arm 32 operates the shaft 35 to shift the cam shaft axially after which the tappets are again lowered on to the new sets of cams. When shifting in the opposite direction, the tappets are raised before the cam shaft is returned to its original position after which the tappets are again lowered on the original set of cams.

In Fig. 5 I have illustrated an engine head 43 provided with an adjustable piston 44 carried on a connecting rod l5 which is operated by a crank 43 on a shaft 41. The shaft is operated by an arm 48 to vary the clearance between the pistons 49 of the engine block and the aligned pistons 44 of the cylinder head to thereby control the amount of compression pressure and therefore the braking force applied to the fly-wheel.

The momentum of the moving vehicle produces the driving force for the engine as it operates as a two-cycle compressor and thereby a braking force is provided which reduces the momentum and nally stops the vehicle.

The operation of the engine and the associated structure above illustrated and described will now be explained. When the engine is employed to drive a load, the cam shaft 2 will be shifted to the left to the position illustrated in Fig. 1. In this position, the pins 9 connect the plate 8 to the plate 'I to thereby have the crankshaft I drive through the gear 4, the gear 3 which operates the cam shaft 2 and the engine as a fourcycle internal combustion engine. This operation continues in the normal manner until such times as the momentum of the load and vehicle increases t0 such an extent as to require a material brake load to be applied to slow up or stop the advancement of the vehicle.

Thereupon, the operator rotates the crank 28 to operate the shaft 22 through the train of gears 2B, 25, 24, and 23. The clockwise rotation of the shaft 22 rotates the cam 2I through the engagement of the pin SI in the forward end of the slot 38. The rotation of the cam 2l operates the roller 2i), arms I9 and Il to raise the tappets I5. After a predetermined rotation of the shaft 22, the pin 42 on the shaft 22 will contact the forward end of the slot 4I of the collar 4U to thereby rotate the link 32 in a clockwise direction. The arm 32 operates the link 33 and the arm 34 through the universal connections 30 disposed therebetween. The arm 34 rotates the shaft 35 which revolves the pin 3T on the end of the arm 38 and shifts the block 38 and the cam shaft 2 to the right. Thereafter, the eccentric 2I passes over the center positioned relative to the roller 2U so that it snaps about the shaft 22, permitting the roller to move in counterclockwise direction along with the arm I9 which lowers the arm I'I and therefore the tappets I5.

It will be noticed after this movement, that the pin 3i engages the rear portion of the slot 30 of the hub 29 so as to be in position to immediately rotate the eccentric 2| in a counterclockwise direction to raise the tappets I before the pin 42 engages the opposite end of the slot 4I from that illustrated in Fig. 4. After the tappets are raised in this manner, the arm 32 is moved in a counterclockwise direction to rotate the shaft 35 to shift the block 38 to the left, thereby returning the cam shaft to its initial position, that illustrated in Fig. 1. Prior to such shifting, the movement of the cam shaft, to the right, as illustrated in Fig. 8, moves the pins 9 within the aperture I 0 in the plate of gear 5 to provide a driving connection between the gears 5 and 6 to thereby operate the cam shaft 2 and the engine as a two- Vstroke cycle compressor.

When the pressure on the piston 49 of the engine head is not sufficient to provide the necessary breaking force when compressing a full charge of air in the cylinder, I employ a movable head or piston so that the volume, and therefore the pressure, may be varied. The head adjacent to each of the pistons 49 is provided with an aperture in the nature of a cylinder, and a piston 44 is mounted therein for movement toward or from the cylinder of the engine block. When operating as a two-cycle compressor, and sufficient power is not obtainable at normal clearance, the piston 44 in the engine head may be adjusted toward the piston 49 in the cylinder of the engine block to decrease the space 39 and therefore the volume to increase the developed pressure and the resulting braking power of the engine. In this manner, the engine produces a braking load on long steep grades where brake bands of conventional form quickly heat and wear out.

While I have described and illustrated but a single embodiment of my invention, it Will be apparent to those skilled in the art, that various changes, omissions, additions, and substitutions may be made therein without departing from the spirit and scope of my invention, as set forth in the accompanying claims.

What I claim is:

1. In combination with an internal combustion engine of the four-stroke cycle type, means for changing the engine operation from a four-stroke cycle internal combustion engine to a two-stroke cycle compressor by simultaneously raising the tappets and shifting the cam shaft of the engine axially and thereafter lowering the tappets.

2. An internal combustion engine having the usual cylinders, pistons, connecting rods and crank shaft, including, in combination, a plurality of valves, tappets for each of said valves, a cam shaft, a series of Cams on said cam shaft engageable with said tappets for operating the engine as a four-stroke cycle engine, a second set of cams on said cam shaft engageable with said tappets for operating the engine as a two-stroke cycle compressor, and means independent of said cam shaft for raising said tappets out of contact with said cams and for shifting said cam shaft axially to align one or the other set of cams therewith.

- 3. An internal combustion engine having the usual cylinders, pistons, connecting rods and crank shaft, including, in combination, intake and exhaust valves, tappets for each of said valves, a cam shaft, a series of cams on said cam shaft engageable with said tappets for operating the engine as a four-stroke cycle engine, a second set of cams on said cam shaft engageable with said tappets for operating the engine as a twostroke cycle compressor, means for shifting said cam shaft axially to align one or the other set of cams therewith, and means for raising said tappets out of contact with said cams prior to the shifting of said cam shaft.

4. An internal combustion engine having the usual cylinders, pistons, connecting rods and crank shaft, including, in combination, intake and exhaust valves, tappets for each of said valves, a cam shaft, a series of cams on said cam shaft engageable with said tappets for operating the engine as a four-stroke cycle engine, a second set of cams on said cam shaft engageable with said tappets for operating the engine as a two-stroke cycle compressor, means for shifting said cam shaft axially to align one or the other set of cams therewith, means for raising said tappets prior to the shifting of said cam shaft, gears for driving said cam shaft from said crank shaft for operation as a four-stroke cycle engine, additional gears interconnecting said cam shaft and said crank shaft for operation as a two-stroke cycle compressor, and means rendering one or the other of said gear sets effective.

5. An internal combustion engine having the usual cylinders, pistons, connecting rods and crank shaft, including, in combination, a plurality of valves, tappets for each of said valves, a cam shaft, a series of cams on said cam shaft engageable with said tappets for operating the engine asa four-stroke cycle engine, a second set of cams on said cam shaft engageable With said tappets for operating the engine as a two-stroke cycle compressor, means for raising said tappets and for shifting said cam shaft axially to align one or the other set of cams therewith, driving means interconnecting the cam shaft and crank shaft for operation as a four-stroke cycle engine, additional driving means interconnecting the cam shaft and crank shaft for operation as a two-stroke cycle compressor, and means for selectively rendering one or the other of said driving means operative.

6. An internal combustion engine having the usual cylinders, pistons, connecting rods and crank shaft, including, in combination, a plurality of valves, tappets for each of said valves, a cam shaft, a series of cams on. said cam shaft engageable with said tappets for operating the engine as a four-stroke cycle engine, a second set of cams on said cam shaft engageable with said tappets for operating the engine as a twostroke cycle compressor, means for iirst raising said tappets above the tcp of said cams and for thereafter shifting said cam shaft axially to align one or the other set of cams therewith, and a lcommon operating means for actuating said raising means for the tappets and for thereafter actuating said cam shaft shifting means and for lowering the tappets.

7. An internal combustion engine having the usual cylinders, pistons, connecting rods and crank shaft, including, in combination, a plurality of valves, tappets for each of said valves, a cam shaft, a series of cams on said cam shaft engageable with lsaid tappets for operating the engine as a four-stroke cycle engine, a second set of cams on said cam shaft engageable with said tappets for operating the engine as a twostroke cycle compressor, means for raising said tappets and for shifting said cam shaft axially to align one or the other set of cams therewith,

and a common operating means for actuating said raising means for the tappets and for thereafter actuating said cam shaft shifting means and for lowering the tappets, said means embodying a spring arm between the tappet lifting means and the cam shaft shifting means.

8. In an internal combustion engine having cylinders, pistons, connecting rods, crank shaft, and intake and exhaust valves, including, in combination, tappets for said valves, means for simultaneously raising all of said tappets, a cam shaft mounted for axial movement, means for axially moving said cam shaft, and flexible means interconnecting the valve lifting means and the cam shaft shifting means.

9. In an internal combustion engine having cylinders, pistons, connecting rods, crank shaft, and intake and exhaust valves, including, in combination, tappets for said valves, means for simultaneously raising all of said tappets, a cam shaft mounted for axial movement, means for axially moving said cam shaft, flexible means interconnecting the valve lifting means and the cam shaft shifting means, means for driving the cam shaft relative to said crank shaft at one rate of speed and means for driving said cam shaft relativeto saidcrank shaft at a different rate of speed, and means for selectively rendering one `or the other of said driving means effective.

l0. In an internal combustion engine, a cam shaft mounted forl axial movement, two sets of cams on said cam shaft, tappets aligned with one set of said cams, means for raising all of said tappets out of contact with all of said cams, and means for thereafter shifting said cam shaft axially.

11. In an internal combustion engine, a cam shaft mounted for axial movement, two sets of cams on said cam shaft, tappets aligned with one of Said sets of Cams, a tappet raising element, a cam operating said element, and a shaft having a loose connection with said cam for producing the rotation thereof.

l2. In an internal combustion engine, a cam shaft mounted for axial movement, two sets of cams on said cam shaft, tappets aligned with one of said sets of cams, a tappet raising element, a cam operating said element, a shaft having a loose connection with said cam for producing the rotation thereof, an arm on said shaft having a lost motion connection therewith, and means operated by said arm for shifting the cam shaft axially.

13. In an internal combustion engine having intake and exhaust valves, a plurality of tappets for said valves, means for raising said tappets, a cam engaging said raising means, a shaft operating said cam having lost motion connection therewith, whereby through rotation of the shaft the cam actuates the raising means for raising the tappets until the cam passes over center relation therewith after which the pressure on the raising means produced by the tappets advances the cam on the shaft and lowers the tappets to initial position while providing engagement between the shaft and the cam for reverse movement.

14. In an internal combustion engine having intake and exhaust valves, a plurality of tappets for said valves, means for raising said tappets, a cam engaging said raising means, a shaft operating said cam having lost motion connection therewith, whereby through rotation of the shaft the cam actuates the raising means for raising the tappets until the cam passes over center relation therewith after which the pressure on the raising means produced by the tappets advances the Cam on the shaft and lowers the tappets to initial position while providing engagement between the shaft and the cam for reverse movement, a cam shaft shiftable axially relative to said tappets, and means operated by said first shaft having lost motion connection therewith for shifting said cam shaft, whereby in either direction of cam shaft movement the tappets will first be raised.

15. In an internal combustion engine having cylinders, pistons, connecting rods, a crank shaft, and intake and exhaust valves including, in combination, tappets for said valves, a cam shaft having one set of cams for operating the tappets in one sequence of engine operation, another set of cams on said cam shaft for operating the tappets in another sequence of engine operation, means for lifting all of the tappets simultaneously out of contact with all of said cams, means for thereafter` shifting said cam shaft from alignment with one set of cams to alignment with the other set of cams, and means thereafter for lowering said lifting means.

CLINTON L. WALKER. 

